The process of cooking in a conventional gas or electric oven is relatively uncomplicated. Generally, temperature and time are the only two cooking parameters considered. Normally, the oven is preheated to a given temperature and the food is placed in the oven for a specified time period which is sometimes determined by the weight of the food. For example, it may be preferable to cook a turkey at 350.degree. F. for 20 minutes per pound. Generally, the heat at the surface of the food gradually travels inward by conduction raising the temperature of the interior and causing physical changes which are part of the cooking process. Because this cooking process is relatively slow and is always limited by the temperature of the oven so that there can be no thermal runaway, there is a reasonable tolerance in the selection of the cooking parameters. For example, a deviation of 10 minutes per hour or 25.degree. F. in temperature may not have a significant impact on the palatability of the cooked food. This tolerance has contributed to a general confidence of most cooks in their ability to accurately select temperature and time, even in new cooking situations. Another contributing factor is exposure in that most cooks grew up in homes where all of the cooking was done in conventional gas or electric ovens.
The microwave oven has evolved in the last two or three decades. Although consumer acceptance has greatly increased as has the percentage of households with microwave ovens, some consumers are still reluctant to buy or use microwave ovens because they don't have the general confidence in their ability to operate them; they feel intimidated by the sometimes complicated directions for using them. They no longer have the comfortable parameters of temperature and time to select. The introduction or indoctrination into a relatively new cooking process is complicated by the rate at which foods cook. More specifically, because a microwave oven cooks so fast, an error of a few minutes in the selected cooking time can be a substantial percentage of the required cooking time and can result in a substantial difference in the doneness of the food. Accordingly, a technique that has been adopted by many if not most microwave cooks is to set the microwave cooking time for less than what they expect it to be and then, after completion of the cycle, to add small amounts of additional heat in sequential cycles until the food arrives at the right state.
Various techniques have been employed to provide the user with simplified operation that gets the food to the right doneness. One such example is described in U.S. Pat. No. 4,390,768, issued June 28, 1983, wherein there is described a scale coupled to the cavity. The weight of the food as positioned in the cavity is coupled directly to a microprocessor along with the food category and the cooking time is automatically calculated and controlled. Another approach is described in U.S. Pat. No. 4,317,977, issued March 2, 1982, wherein controls are provided for selecting between rare and well-done; the controls alter the desired final temperature which is used to determine when the cooking process terminates. Both of these techniques, however, have drawbacks. More specifically, if the operator controls the oven according to the simplified methods described therein and the food is not done to the desired state, there are no provisions for altering the process.